PPP, or Point-to-Point Protocol, operates at the data link layer, which is also known as layer 2 in the OSI model. This layer is responsible for handling the physical transmission of data between two directly connected nodes, such as two routers. PPP establishes a reliable link between these nodes before higher-level protocols, like IP, can transmit data.
Several sources confirm this:
- Wikipedia: Explicitly states PPP is a "data link layer (layer 2) communication protocol".
- TechTarget: Describes PPP as a protocol used on various physical media, implying a layer 2 function.
- Multiple Cisco Community Posts: Discussions about PPP consistently place it at layer 2.
- Baeldung: Clearly states PPP "directly connects two network devices at the data link layer".
- Juniper Networks Community: Mentions Layer 2 PPP sessions.
While PPP utilizes a Network Control Protocol (NCP) to negotiate and configure higher-layer protocols (like IP at layer 3), its core functionality remains firmly at layer 2, managing the physical link and ensuring reliable data transmission between the two points. Think of it as the bridge that ensures that layer 3 and higher can function effectively.
